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Blog

Selecting Gasket for Round & Oval Ductwork: Understanding Open vs. Closed-Cell Foam

Posted on September 25, 2025 by Ductmate Industries

When sealing round or flat oval ductwork, foam gasket tape is often used to create an airtight seal, maintain energy efficiency, and ensure proper airflow; however, not all foams are created equal. Understanding the difference between open-cell and closed-cell foam is crucial for ensuring a proper seal and avoiding costly mistakes when choosing your materials.

What’s the Difference Between Open and Closed-Cell Foam?

The primary difference between open-cell and closed-cell foam lies in their internal structure.

Open-cell foam has interconnected air pockets, making it highly permeable to air and water. While it’s excellent for cushioning or sound absorption, its permeability prevents it from forming an airtight or watertight seal, similar to a sponge. This can lead to air leaks, moisture absorption, and potential mold growth in HVAC systems.

Due to its permeability, open-cell foam is generally not suitable for sealing ductwork. It is more commonly used for projects that require acoustic absorption, padding and cushioning, such as in furniture and bedding, as well as for air sealing where moisture isn’t an issue, like in interior walls and attics.

Closed-cell foam, on the other hand, is composed of individual, sealed cells that resemble tiny balloons packed tightly together. This structure makes the foam highly resistant to air and moisture, making it ideal for insulation and sealing. It is also denser and more durable than open-cell foam, resisting compression set, which is the tendency for it to lose its thickness after being compressed.

While both open and closed-cell foam have their uses, closed-cell foam is the clear choice for ductwork because it creates an effective seal by resisting air and moisture, preventing leaks and condensation.

Why is Neoprene Gasket the Best Option for Round & Oval Ductwork?

Among the closed-cell foam gasket options, neoprene is a superior material made from synthetic rubber, ideal for sealing round and flat oval ductwork. Its unique advantages make it the best choice for ensuring a reliable and long-lasting seal.

  • Excellent Sealing Properties: Closed-cell neoprene provides a firm, airtight seal, which is critical for preventing air leaks in round and flat oval ductwork. Its ability to conform to irregular surfaces while maintaining integrity ensures a reliable seal.
  • Durability and Resilience: Neoprene is highly resilient and resistant to compression set. This means it can withstand the constant pressure and vibration common in HVAC systems without losing its shape or sealing effectiveness over time.
  • Flexibility: While durable, neoprene remains flexible, which is essential for creating a tight seal around the curved surfaces of round ductwork. This flexibility allows it to compress evenly around the flanges.
  • Clean & Simple Removal: The resilient nature of neoprene foam makes it easy to remove from ductwork without leaving behind a sticky residue or falling apart. This simplifies the process of disassembling ductwork for periodic cleaning or maintenance, allowing for a quick and easy application of new gasket tape to reseal the connection.

Where Can I Buy Ductmate’s Neoprene Gasket Tape?

Ready to buy our neoprene gasket tape?  Ductmate products are available at over 350 locations across the US as part of a selective distribution network.  Use the Ductmate distributor locator map to find a distributor near you.

Outside the US? Check out our international distributor list.  For detailed information on product availability, lead times, or other international sales requests, please email ductmate@ductmate.com.

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Ductmate Announces the Passing of William “Bill” Bradford Jr

Posted on January 6, 2023 by Ductmate Industries

Sheet Metal Industry Icon, Ductmate’s First Foreman Passes Away at 85

Ductmate Industries, leadership and employees are saddened to report that William “Bill” Bradford Jr., 85, passed away peacefully with his family by his side on Sunday, Jan. 1, 2023.

Bill was a colleague and mentor to many in the sheet metal industry, as well as the first SNIPS Industry Icon. With over 55 years of experience, he was Ductmate Industries’ first shop foreman hired after the company’s inception in 1978. Bill assisted Peter J. Arnoldt, one of the founders of Ductmate, in building the original Ductmate 35 production line and spent countless hours perfecting the product that revolutionized the HVAC industry.

Once production began, Bill managed and directed Ductmate’s first group of employees to staff the factory. He trained hundreds of sheet metal workers and customers to properly install the Ductmate 25/35 Systems and quickly advanced within the organization. Bill held the following positions throughout his time at Ductmate: Foreman, Factory Superintendent, Field Service Manager and National Service Manager.

From his early days of running the Ductmate facility to traveling and working with contractors, end users and distributors, Bill’s impact on the sheet metal and HVAC industry cannot be overstated.

Bill was born on Aug. 13, 1937, in Pittsburgh to the late William and Frances (Matuszewski) Bradford Sr. and graduated from Oliver High School in 1955. Following graduation, he served for four years in the U.S. Airforce. Upon honorable discharge, he wished to continue his service by joining the Air Force Reserve, followed by the Pennsylvania Air National Guard, serving twenty more years.

Bill joined Ductmate in 1978 for his distinguished 32-year career. Although he officially retired in 2009, Bill remained a staple at training classes and industry events through 2019, sharing his knowledge with future generations of employees, sheet metal workers and customers for 10 years post-retirement.

Bill is survived by his high school sweetheart and wife of over 61 years, Joanne (Kaiser) Bradford, Joanne’s sister Jeanne J. Zeigler; his children Renee J. (Shawn) Pennington, William C. (Lori) Bradford; his grandchildren Ryan B. Pennington, Evan L. (Brenna) Pennington, Aila M. (Joshua) Freed, Hannah J. Bradford and William “Tanner” Bradford; his great-grandchildren Logan R. Pennington and baby-to-be Freed; his siblings Richard (Jane) Bradford, Terry (Christine) Bradford and Donna L. (Robert) Cunningham, as well as many nieces and nephews.

Bill considered the employees of Ductmate his second family. Throughout his career, he touched the hearts of many Ductmate employees and industry professionals. As a tribute, The William Bradford Training Center at DMI’s corporate headquarters in Charleroi was dedicated to him over a decade ago. Bill Bradford Jr. created a legacy within the industry and with Ductmate that ensures that he will be missed but never forgotten.

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Ductmate’s First Employee Bill Bradford Honored in SNIPS Magazine

Posted on October 4, 2019 by Ductmate Industries

How Bill Bradford became a legend at Ductmate Industries

Bill Bradford’s sheet metal career is the embodiment of the phrase “standing on the shoulders of giants.” Only, in this story, Bradford is one of the giants.

Bill Bradford is a veteran of the sheet metal industry in more ways than most.

Born and raised in North Side Pittsburgh, Pennsylvania, during the city’s “Steel City” renaissance, Bradford graduated from high school June 1955 and immediately joined the Air Force that July. “I was 17 so my parents had to sign documents to get me in,” he remembers. His dad, a truck driver, was gone on the road a lot while his mom worked different jobs to make ends meet. “Upbringing was normal in that we did not have a lot but did not want for anything,” he says, the oldest of two brothers and two sisters. The service was his chance to fight for his country while learning skills to build a future.

“College was not for me,” Bradford says, simply. Around age 23, a job repairing fighter jets for the National Guard became his ticket into the sheet metal industry, and soon he signed up for his first apprenticeship. “I did not want to go to college with that experience from the Guard,” he explains, “so I joined the Pittsburgh Local 12 Sheet Metal Apprenticeship program.” He adds, “Where else can you start a career and make a great living right out of the gate?”

Now at 82 years old and retired, Bradford is celebrated as part of the early generation of tin knockers who made making a living in the sheet metal industry possible. “I miss the great trade, the great people that I worked with over the many years,” he says. “Right now, we cannot hire enough sheet metal workers as there is so much work to be done across the country.” The bulk of Bradford’s part in that work began in the ’70s.

On a scale of 1 to 10, “Sheet metal work was a 10 back then,” Bradford says. “What made it difficult was all electric corded tools; we had to build scaffolding; there were no GLG lifts, heavy wooden ladders, no Tek screws, all pan head screws that had to be screwed in with flat blade screw driver, a lot of heavy manual lifting of ductwork,” the list goes on. However, that never stopped Bradford from getting the job done, and the downtown Pittsburgh skyline flaunts his resume. Installing the U.S. Steel Tower’s large HVAC system, “We also installed very large drop ceilings that were part of our scope of work,” he explains. “They were approximately 5 feet by 3 feet and 3 inches thick. No Ductmate-type connectors at that time.” Today’s PNC Park and Heinz Field stadiums are also at the location of another Bradford assisted project, the former Three Rivers Stadium (built in 1970 and demolished in 2000). “The coldest job ever,” he remembers. “Heavy ladders were hard to move around and the weather conditions were horrible.”

In 1978, Bradford made the career jump from field metalwork to manufacturing duct products as the first employee for a little-known company at the time called Ductmate Industries (now DMI Companies) under founder Peter Arnoldt. At 40 years old, Bradford welcomed the “lucky opportunity” to give his body a break from the everyday grunt work and extend his career.

“I received a call from one of the Ductmate owners about the possibility of a job. I talked it over with the foreman at my current company and he told me that Ductmate was a new company and he did not know much about it,” he remembers. “The good thing was, he told me to give it a shot and if it does not work out you can come back.” After a month, Bradford knew the company would be a success, he says. “I thought the company would be a success because of the type of connection they were going to introduce to the industry.”

The Ductmate 35 Flange was the first product line. “Peter (Arnoldt) chose that as the first one. I helped him set up the first roll former to get the 35 out the door. We were on a shoestring budget getting that first roll former up and running. We spent many nights and weekends working overtime to get that very first piece of equipment running properly,” says Bradford, and he wore more than a few hats in the process as general superintendent and national service manager. “I ran the shop, ran the roll former and did the purchasing. If we had field installation problems, Peter would send me to troubleshoot and fix the problem.”

The most common problem with field installations at the time was that contractors were not reading the installation instructions, he explains. “When they read the installation documentation, the installs went well. We made automated equipment to help contractors install Ductmate Flange better and faster. Some of these were the Ductmater, Autosealer and Super Welder. Peter invented all of these pieces of equipment.”

As the company took off and started to expand in the late ’80s, Bradford took on a role that most people today know him for: mentor.

“My first meeting with Bill Bradford, who supervised me at the time, sticks out in mind,” says Doug Gudenburr, now chief operating officer at DMI Companies. “We were young, snot-nosed, knew everything, and he would chase us around and shake his head sometimes. But at the end of the day, I think we really appreciated him and he appreciated us. At that time the general concept and mentality of the folks was whatever it took to get the job done. We played hard but we certainly worked hard, and that’s something I will always remember about Bill.”

Under Bradford’s whatever-it-takes-to-get-the-job-done style, future leaders were made that could efficiently manage the company’s operations into success. The William Bradford Training Center at DMI’s headquarters in Charleroi, Pennsylvania, pays homage to that success.

“I decided to retire as I had the proper people in place to take over my responsibilities,” says Bradford. “We had good people at Ductmate so I was not worried that the success we had would continue.” And it has.

“The generations of workers that Bill has trained, it could be countless. From his early days of running the facility to being on the road and working with contractors and users and distributors, different sales forces that have come and gone over the time. Many people at this point are either retired or frankly not with us any longer,” says Gudenburr. “It’s just a whole new group of people Bill has touched as time has gone on with his tenure in the company.”

Original Article On SnipsMag.com

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